You might try getting a really tiny axe and going in after them...just kidding... There are a variety of schools of thought on this matter and depending on the size of the plants some work better than others. Have any more info about THEM DAMN spidermites and the plants you are growing? I like drowning them if the plants are small enough but I do not ever try to dunk large plants, lets just say I had a bad experience once. Drowning them cleaning the plants and bleaching the area is an excellent method that does not require poison or money really. You could wash each leaf on the plants off with a very mild soap and water or many just water and a soft rag or sponge. I have done this before and it works it is just very hard to get them all if the plant is much larger than a foot or so I have found. Some people love fogging poison or sulfur in the room. I know this works as my aunt owns greenhouse and uses this very method. It is a mess if you are in a house or a bedroom and to much sulfur can be toxic to you. You can build your own from guides online though. A burner is cheap like that but I question its safety in the long run if you look at those plans. Of course things like neem can help and there are products like Azamax that do a wonderful job if used correctly and at the right intervals. The sure fire method to get rid of them is kill all plants empty room sterilize room get new clean plants start over. If you use tents I have found that bleaching the tent out every 2 or 3 weeks pretty much keeps them away for good as long as they were never in there. Cleanliness is the most important thing in general. You can find more info all over this site and the internet... I will leave the searching to you however.